Re: #u3s Relocating R5 #u3s
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Well let’s not kid ourselves here. The IRF parts and the RD parts are very (very very) different animals. The IRF510’s dies are hard-on switches, meaning they saturate/ switch on hard and abruptly…they are designed that way because of their actual intended service as motor switches and power supply parts…. and that, in an RF world can cause harmonics, ringing, and trash. It means you need to work extra hard to filter that stuff out of your output signal when you push them… and it’s frequency dependent. The RD devices are made to be RF switches with a smoother approach on the curve at full on. Much less trash generated. You already know about the capacitance issues.
Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
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Big Signal Ranch – K9ZC
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Moderator – North American QRO Group at Groups.IO.
From: QRPLabs@groups.io [mailto:QRPLabs@groups.io] On Behalf Of ajparent1/KB1GMX
for a 5W amplifier the RD15HHF or RD16VHF is a over sized device.